InfoPath Dev

Hi All, I designed an Infopath form which has a repeating table followed by another repeating table in an optional section in a repeating section. At the end of each repeating table I have the sum of a column. I also have further down (outside the repeating section) a Total of all the sum fields . In the Total field I have the error "Nan", but it disappear when I open the optional section. What should I do for the Total field to display the result even if the optional section is “closed”. Hope I was clear enough, thank you in advance.

What's the formula for the total field? Click the Edit XPath checkbox and paste in the full formula - as well as the XPath to the Optional section field....

Thank you but I have found the solution right after publishing my post and I couldn't delete it. I didn't need the 1st repeating table nor the optional section. I simplified the form and now the sum are working in the repeating table.